Communication schemes in which radio resources are divided in an edge area relatively near the edge of a cell in a radio communication system and are shared with adjacent cells have been proposed. Examples of the communication schemes include fractional frequency reuse (FFR). The above communication schemes are also applied when one cell is divided into a plurality of sectors, in order to share radio resources between adjacent sectors. In the following description, for ease of understanding, the area covered by a base station device is generally referred to as a “cell” regardless of whether the minimum unit of the covered area is “cell” or “sector”.
A method has been proposed including receiving an uplink signal via a radio antenna of a mobile communication base station; extracting inter-cell interference amount information from the received uplink signal; generating uplink control information based on the inter-cell interference amount information; and transmitting the generated uplink control information to a mobile communication terminal located in an adjacent cell, wherein the terminal schedules an uplink resource by referring to the uplink control information.
Also proposed has been a mobile communication system which enables radio base stations to communicate with each other using a link between the base stations, in which the radio base stations are notified of information about radio environments of adjacent cells and in which the latest version of the information about the radio environments is stored in a memory of each of the radio base stations so that each radio base station can perform handover control, transmission power control, traffic control, and the like by referring to the information stored in the memory.
Also proposed has been a code division multiple access (CDMA) mobile communication system in which traffic control is performed independently for the uplink and the downlink in accordance with transmission power control based on communication quality so that different base stations can be selected for the uplink and the downlink.
Also proposed has been a method for reusing orthogonal frequency division multiplex frequency resources in a mobile communication system including a plurality of base stations that communicate with terminals using the orthogonal frequency division multiplex method. This method includes dividing orthogonal frequency division multiplex frequency resources available to each base station into at least four groups; setting frequency reuse distance values so that each of the obtained groups of orthogonal frequency division multiplex frequency resources can have the same frequency reuse distance value or different frequency reuse distance values; and sequentially allocating the groups of orthogonal frequency division multiplex frequency resources to cell areas of each base station in such a manner that a group of orthogonal frequency division multiplex frequency resources having a small frequency reuse distance value is allocated to a nearby cell area and a group of orthogonal frequency division multiplex frequency resources having a large frequency reuse distance value is allocated to a remote cell area.
Examples of related art are as follows: Japanese Laid-open Patent Publications No. 2008-61250, No. 2007-295318, No. 2000-269881, and No. 2004-159345; S. Faruque, “High capacity cell planning based on fractional frequency reuse with optimum trunking efficiency”, the 48th IEEE Vehicular Technology Conference, 1998 (VTC 98), vol. 2, pp. 1458-1460, May 1998; “Fractional Frequency Reuse in Mobile WiMAX”, accessed Jul. 17, 2009 at http://www.conniq.com/WiMAX/fractional-frequency-reuse.htm; “Flexible Fractional Frequency Reuse Approach”, Samsung, 3GPP TSG RAN WG1 Meeting #43 (R1-051341), Nov. 7-11, 2005; and KONISHI Satoshi et al., “A Study on the Fractional Frequency Reuse for the OFDMA-based cellular systems”, the Institute of Electronics, Information and Communication Engineers, Communication Society Conference, B-5-59, September 2007.
In an edge area where radio resources are divided and shared between adjacent cells, the radio propagation distance between a base station device and a mobile station device is long. Thus, the communication throughput between the base station device and the mobile station device is reduced. In the edge area, furthermore, radio resources are divided and shared with the edge area of an adjacent cell. Thus, the amount of radio resources allocated to each edge area is reduced and therefore the communication throughput between the base station device and the mobile station device is reduced.